Nitrogen and phosphorus co-doped graphene quantum dots: synthesis from adenosine triphosphate, optical properties, and cellular imaging.

Arundithi Ananthanarayanan,Parimal Routh,Jie Chen,Mahasin Alam Sk,Peng Chen,Aung Than,Ming Lin,Jie Zhang,Handong Sun,Yue Wang

doi:10.1039/c5nr01519g

Abstract

Graphene quantum dots (GQDs) are emerging zero-dimensional materials promising a wide spectrum of applications, particularly, as superior fluorescent reporters for bio-imaging and optical sensing. Heteroatom doping can endow GQDs with new or improved photoluminescence properties. Here, we demonstrate a simple strategy for the synthesis of nitrogen and phosphorus co-doped GQDs from a single biomolecule precursor (adenosine triphosphate - ATP). Such ATP-GQDs exhibit high fluorescence quantum yield, strong two-photon upconversion, small molecular weight, high photostability, and good biocompatibility. Furthermore, transferrin conjugated ATP-GQDs have been used for imaging and real-time tracking of transferrin receptors in live cells.

Highlights

Graphene quantum dots (GQDs) are a new class of zero-dimensional nanomaterials, which have shown immense potential for bioimaging, optical sensing, energy conversion, and catalysis.[1,2,3,4] Owing to their tunable photoluminescence (PL), photostability, molecular size, biocompatibility, and the ease of conjugation with biomolecules, GQDs are attractive for bioimaging.[5,6,7,8,9,10,11,12,13,14,15] It has been shown that heteroatom doping can endow GQDs with tailored or new PL as well as other properties.[15,16,17] Heteroatom-doped GQDs can be synthesized by exfoliating pre-doped graphene or graphene oxide sheets,[18,19,20,21] but such top-down methods are tedious because of the need for multiple steps and because they are usually of low doping efficiency
Carbonaceous micro-sheets resulting from adenosine triphosphate (ATP) carbonization exhibit good catalytic properties towards oxygen reduction, and heteroatom-doped Graphene quantum dots (GQDs) conjugated with transferrin have been employed to image and track transferrin receptors in live cells
Linear sweep voltammograms of carbonized ATP (cATP) in oxygen-saturated 0.1 M KOH are obtained using a rotating disk electrode at various rotating speeds to determine the number of electrons transferred for the oxygen reduction reaction (ORR) process (Fig. 1d)

Summary

Introduction

Graphene quantum dots (GQDs) are a new class of zero-dimensional nanomaterials, which have shown immense potential for bioimaging, optical sensing, energy conversion, and catalysis.[1,2,3,4] Owing to their tunable photoluminescence (PL), photostability, molecular size, biocompatibility, and the ease of conjugation with biomolecules, GQDs are attractive for bioimaging.[5,6,7,8,9,10,11,12,13,14,15] It has been shown that heteroatom doping can endow GQDs with tailored or new PL as well as other properties.[15,16,17] Heteroatom-doped GQDs can be synthesized by exfoliating pre-doped graphene or graphene oxide sheets,[18,19,20,21] but such top-down methods are tedious because of the need for multiple steps and because they are usually of low doping efficiency. We report a simple and cost-effective method for the synthesis of GQDs co-doped with nitrogen, and phosphorus by carbonization and subsequent chemical exfoliation of a single precursor molecule – adenosine triphosphate (ATP) (Scheme 1, see the Experimental section).

Results

Conclusion